1. Field of the Invention
The present invention relates to operations in a wellbore. More specifically, the invention relates to a system and method for mitigating hazards associated with use of a drill string.
2. Description of the Related Art
Hydrocarbon producing wellbores extend subsurface and intersect subterranean formations where hydrocarbons are trapped. The wellbores generally are created by drill bits that are on the end of a drill string, where a drive system above the opening to the wellbore rotates the drill string and bit. Cutting elements are usually provided on the drill bit that scrape the bottom of the wellbore as the bit is rotated and excavate material thereby deepening the wellbore. Drilling fluid is typically pumped down the drill string and directed from the drill bit into the wellbore. The drilling fluid flows back up the wellbore in an annulus between the drill string and walls of the wellbore. Cuttings produced while excavating are carried up the wellbore with the circulating drilling fluid. Drill strings are typically made up of tubular sections attached by engaging threads on ends of adjacent sections to form threaded connections. New tubular sections are attached to the upper end of the drill string as the wellbore deepens and receives more of the drill string therein. Drill string rotation is temporarily suspended each time a tubular section is added to the drill string.
To overcome dynamic losses in the drill string while drilling, sometimes high solids mud and or large amounts of loss circulation material (LCM) are pumped downhole. These solids can plug the drill string thus preventing fluid from flowing through the drill bit. If the well starts to produce while the drill string is plugged, flow cannot be circulated through the drill string to kill the well, thereby introducing the possibility of a blowout. Another undesirable situation resulting from a plugged drill string is that the drill string can become stuck against the wellbore wall.